1. Field of the Invention
The present invention relates to a webbing locking device for locking an intermediate portion of an occupant restraining webbing, adapted for use in a seatbelt system for restraining an occupant of a vehicle, particularly, suitable to assemble the same into a webbing retractor disposed on a ceiling of the vehicle.
2. Description of the Prior Art
A webbing retractor is constructed such that a a webbing takeup shaft is secured with one end portion of an occupant restraining webbing and it is rotated in a direction of a webbing winding by a biasing force of a spiral spring so that the webbing can be wound in layers on the takeup shaft. Also, the webbing retractor is generally fixed to a side wall of the vehicle and the webbing which has been unwound from the takeup shaft is turned back at a slip joint mounted on an upper portion of the vehicle and, thereafter, it is applied to the occupant as a shoulder webbing.
In such a seatbelt system, since the webbing is turned back sharp at the slip joint, there is such a problem that a frictional resistance between the webbing and the slip joint is increased when the webbing is moved.
In order to overcome the above problem such a system has been proposed that the webbing retractor is mounted on a side of the ceiling or an upper side of a center pillar of the vehicle and the webbing is drawn out through an opening of a panel of the ceiling or the center pillar. In this case the webbing is slightly turned at the opening, an angle of which is small, so that a frictional resistance between the webbing and the opening becomes small when the webbing is moved.
On the other hand, the webbing retractor is generally provided therein with a webbing locking device for preventing the webbing from unwinding in an emergency situation of the vehicle. The webbing locking device can roughly be classified in two types, one type-being directed to a locking mechanism comprising a combination of a ratchet wheel fixed to the takeup shaft and a pawl engaged with the ratchet wheel and the other type being directed to a locking mechanism disposed adjacent to the webbing retactor, in which a pair of lock members clip, or lock, the webbing in the emergency situation of the vehicle.
In the former type mechanism, however, there is such a problem that a winding diameter of the webbing retactor must be made large. In the latter type, also, there is such a fear that when a large drawing-out force acts upon the webbing the webbing is slipped out and there is such a problem that such acceleration sensing means as an inertia weight can not be applied directly to the same since a large force is required in order to operate the pair of lock members.